[Openvpn-devel,v6] Add --tls-cert-profile option for mbedtls builds

Message ID	20171112163636.17434-1-steffan@karger.me
State	Accepted
Headers	show Return-Path: <openvpn-devel-bounces@lists.sourceforge.net> From: Steffan Karger <steffan@karger.me> To: openvpn-devel@lists.sourceforge.net Date: Sun, 12 Nov 2017 17:36:36 +0100 Message-Id: <20171112163636.17434-1-steffan@karger.me> In-Reply-To: <5f8d8043-5725-f535-e623-da042984196b@unstable.cc> References: <5f8d8043-5725-f535-e623-da042984196b@unstable.cc> RBL: Sender listed at http://www.dnswl.org/, no trust [209.85.128.176 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature Subject: [Openvpn-devel] [PATCH v6] Add --tls-cert-profile option for mbedtls builds Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: openvpn-devel-bounces@lists.sourceforge.net X-getmail-retrieved-from-mailbox: Inbox
Series	[Openvpn-devel,v6] Add --tls-cert-profile option for mbedtls builds \| expand [Openvpn-devel,v6] Add --tls-cert-profile option for mbedtls builds

diff --git a/Changes.rst b/Changes.rst index db9b18b9..a6090cf5 100644 --- a/Changes.rst +++ b/Changes.rst @@ -321,6 +321,18 @@ Maintainer-visible changes i386/i686 builds on RHEL5. +Version 2.4.5 +============= + +New features +------------ +- The new option ``--tls-cert-profile`` can be used to restrict the set of + allowed crypto algorithms in TLS certificates in mbed TLS builds. The + default profile is 'legacy' for now, which allows SHA1+, RSA-1024+ and any + elliptic curve certificates. The default will be changed to the 'preferred' + profile in the future, which requires SHA2+, RSA-2048+ and any curve. + + Version 2.4.3 ============= diff --git a/doc/openvpn.8 b/doc/openvpn.8 index a4189ac2..549d96cb 100644 --- a/doc/openvpn.8 +++ b/doc/openvpn.8 @@ -4917,6 +4917,37 @@ when using mbed TLS or OpenSSL. .\"********************************************************* .TP +.B \-\-tls\-cert\-profile profile +Set the allowed cryptographic algorithms for certificates according to +.B profile\fN. + +The following profiles are supported: + +.B legacy +(default): SHA1 and newer, RSA 2048-bit+, any elliptic curve. + +.B preferred +: SHA2 and newer, RSA 2048-bit+, any elliptic curve. + +.B suiteb +: SHA256/SHA384, ECDSA with P-256 or P-384. + +This option is only fully supported for mbed TLS builds. OpenSSL builds use +the following approximation: + +.B legacy +(default): sets "security level 1" + +.B preferred +: sets "security level 2" + +.B suiteb +: sets "security level 3" and \-\-tls\-cipher "SUITEB128". + +OpenVPN will migrate to 'preferred' as default in the future. Please ensure +that your keys already comply. +.\"********************************************************* +.TP .B \-\-tls\-timeout n Packet retransmit timeout on TLS control channel if no acknowledgment from remote within diff --git a/src/openvpn/init.c b/src/openvpn/init.c index 1ed2c55e..cccc63b2 100644 --- a/src/openvpn/init.c +++ b/src/openvpn/init.c @@ -1016,7 +1016,8 @@ print_openssl_info(const struct options *options) } if (options->show_tls_ciphers) { - show_available_tls_ciphers(options->cipher_list); + show_available_tls_ciphers(options->cipher_list, + options->tls_cert_profile); } if (options->show_curves) { diff --git a/src/openvpn/options.c b/src/openvpn/options.c index 49ed004b..9d6e279a 100644 --- a/src/openvpn/options.c +++ b/src/openvpn/options.c @@ -599,6 +599,8 @@ static const char usage_message[] = #endif "--tls-cipher l : A list l of allowable TLS ciphers separated by : (optional).\n" " : Use --show-tls to see a list of supported TLS ciphers.\n" + "--tls-cert-profile p : Set the allowed certificate crypto algorithm profile\n" + " (default=legacy).\n" "--tls-timeout n : Packet retransmit timeout on TLS control channel\n" " if no ACK from remote within n seconds (default=%d).\n" "--reneg-bytes n : Renegotiate data chan. key after n bytes sent and recvd.\n" @@ -872,6 +874,7 @@ init_options(struct options *o, const bool init_gc) o->renegotiate_seconds = 3600; o->handshake_window = 60; o->transition_window = 3600; + o->tls_cert_profile = NULL; o->ecdh_curve = NULL; #ifdef ENABLE_X509ALTUSERNAME o->x509_username_field = X509_USERNAME_FIELD_DEFAULT; @@ -1750,6 +1753,7 @@ show_settings(const struct options *o) SHOW_STR(cryptoapi_cert); #endif SHOW_STR(cipher_list); + SHOW_STR(tls_cert_profile); SHOW_STR(tls_verify); SHOW_STR(tls_export_cert); SHOW_INT(verify_x509_type); @@ -2729,6 +2733,7 @@ options_postprocess_verify_ce(const struct options *options, const struct connec MUST_BE_UNDEF(pkcs12_file); #endif MUST_BE_UNDEF(cipher_list); + MUST_BE_UNDEF(tls_cert_profile); MUST_BE_UNDEF(tls_verify); MUST_BE_UNDEF(tls_export_cert); MUST_BE_UNDEF(verify_x509_name); @@ -7831,6 +7836,11 @@ add_option(struct options *options, VERIFY_PERMISSION(OPT_P_GENERAL); options->cipher_list = p[1]; } + else if (streq(p[0], "tls-cert-profile") && p[1] && !p[2]) + { + VERIFY_PERMISSION(OPT_P_GENERAL); + options->tls_cert_profile = p[1]; + } else if (streq(p[0], "crl-verify") && p[1] && ((p[2] && streq(p[2], "dir")) || (p[2] && streq(p[1], INLINE_FILE_TAG) ) || !p[2]) && !p[3]) { diff --git a/src/openvpn/options.h b/src/openvpn/options.h index 496c1143..85ff200b 100644 --- a/src/openvpn/options.h +++ b/src/openvpn/options.h @@ -502,6 +502,7 @@ struct options const char *priv_key_file; const char *pkcs12_file; const char *cipher_list; + const char *tls_cert_profile; const char *ecdh_curve; const char *tls_verify; int verify_x509_type; diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index cb94229a..359ef635 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -616,6 +616,9 @@ init_ssl(const struct options *options, struct tls_root_ctx *new_ctx) tls_ctx_client_new(new_ctx); } + /* Restrict allowed certificate crypto algorithms */ + tls_ctx_set_cert_profile(new_ctx, options->tls_cert_profile); + /* Allowable ciphers */ /* Since @SECLEVEL also influces loading of certificates, set the * cipher restrictions before loading certificates */ diff --git a/src/openvpn/ssl_backend.h b/src/openvpn/ssl_backend.h index aba5a4de..f588110c 100644 --- a/src/openvpn/ssl_backend.h +++ b/src/openvpn/ssl_backend.h @@ -176,6 +176,16 @@ void tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags); */ void tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers); +/** + * Set the TLS certificate profile. The profile defines which crypto + * algorithms may be used in the supplied certificate. + * + * @param ctx TLS context to restrict, must be valid. + * @param profile The profile name ('preferred', 'legacy' or 'suiteb'). + * Defaults to 'preferred' if NULL. + */ +void tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile); + /** * Check our certificate notBefore and notAfter fields, and warn if the cert is * either not yet valid or has expired. Note that this is a non-fatal error, @@ -505,9 +515,12 @@ void print_details(struct key_state_ssl *ks_ssl, const char *prefix); * Show the TLS ciphers that are available for us to use in the OpenSSL * library. * - * @param - list of allowed TLS cipher, or NULL. + * @param cipher_list list of allowed TLS cipher, or NULL. + * @param tls_cert_profile TLS certificate crypto profile name. */ -void show_available_tls_ciphers(const char *tls_ciphers); +void +show_available_tls_ciphers(const char *cipher_list, + const char *tls_cert_profile); /* * Show the available elliptic curves in the crypto library diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c index 861d936d..09829ebb 100644 --- a/src/openvpn/ssl_mbedtls.c +++ b/src/openvpn/ssl_mbedtls.c @@ -62,6 +62,34 @@ #include <mbedtls/pem.h> #include <mbedtls/sha256.h> +static const mbedtls_x509_crt_profile openvpn_x509_crt_profile_legacy = +{ + /* Hashes from SHA-1 and above */ + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA1 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_RIPEMD160 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ), + 0xFFFFFFF, /* Any PK alg */ + 0xFFFFFFF, /* Any curve */ + 1024, /* RSA-1024 and larger */ +}; + +static const mbedtls_x509_crt_profile openvpn_x509_crt_profile_preferred = +{ + /* SHA-2 and above */ + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 ) | + MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ), + 0xFFFFFFF, /* Any PK alg */ + 0xFFFFFFF, /* Any curve */ + 2048, /* RSA-2048 and larger */ +}; + +#define openvpn_x509_crt_profile_suiteb mbedtls_x509_crt_profile_suiteb; + void tls_init_lib(void) { @@ -250,6 +278,27 @@ tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers) free(tmp_ciphers_orig); } +void +tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile) +{ + if (!profile || 0 == strcmp(profile, "legacy")) + { + ctx->cert_profile = openvpn_x509_crt_profile_legacy; + } + else if (0 == strcmp(profile, "preferred")) + { + ctx->cert_profile = openvpn_x509_crt_profile_preferred; + } + else if (0 == strcmp(profile, "suiteb")) + { + ctx->cert_profile = openvpn_x509_crt_profile_suiteb; + } + else + { + msg (M_FATAL, "ERROR: Invalid cert profile: %s", profile); + } +} + void tls_ctx_check_cert_time(const struct tls_root_ctx *ctx) { @@ -917,6 +966,8 @@ key_state_ssl_init(struct key_state_ssl *ks_ssl, mbedtls_ssl_conf_rng(&ks_ssl->ssl_config, mbedtls_ctr_drbg_random, rand_ctx_get()); + mbedtls_ssl_conf_cert_profile(&ks_ssl->ssl_config, &ssl_ctx->cert_profile); + if (ssl_ctx->allowed_ciphers) { mbedtls_ssl_conf_ciphersuites(&ks_ssl->ssl_config, ssl_ctx->allowed_ciphers); @@ -1271,12 +1322,14 @@ print_details(struct key_state_ssl *ks_ssl, const char *prefix) } void -show_available_tls_ciphers(const char *cipher_list) +show_available_tls_ciphers(const char *cipher_list, + const char *tls_cert_profile) { struct tls_root_ctx tls_ctx; const int *ciphers = mbedtls_ssl_list_ciphersuites(); tls_ctx_server_new(&tls_ctx); + tls_ctx_set_cert_profile(&tls_ctx, tls_cert_profile); tls_ctx_restrict_ciphers(&tls_ctx, cipher_list); if (tls_ctx.allowed_ciphers) diff --git a/src/openvpn/ssl_mbedtls.h b/src/openvpn/ssl_mbedtls.h index f69b6100..341da7d4 100644 --- a/src/openvpn/ssl_mbedtls.h +++ b/src/openvpn/ssl_mbedtls.h @@ -82,6 +82,7 @@ struct tls_root_ctx { struct external_context *external_key; /**< Management external key */ #endif int *allowed_ciphers; /**< List of allowed ciphers for this connection */ + mbedtls_x509_crt_profile cert_profile; /**< Allowed certificate types */ }; struct key_state_ssl { diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c index 0bfb6939..de89cb13 100644 --- a/src/openvpn/ssl_openssl.c +++ b/src/openvpn/ssl_openssl.c @@ -383,6 +383,40 @@ tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers) } } +void +tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile) +{ +#if (OPENSSL_VERSION_NUMBER >= 0x10100000) + /* OpenSSL does not have certificate profiles, but a complex set of + * callbacks that we could try to implement to achieve something similar. + * For now, use OpenSSL's security levels to achieve similar (but not equal) + * behaviour. */ + if (!profile || 0 == strcmp(profile, "legacy")) + { + SSL_CTX_set_security_level(ctx->ctx, 1); + } + else if (0 == strcmp(profile, "preferred")) + { + SSL_CTX_set_security_level(ctx->ctx, 2); + } + else if (0 == strcmp(profile, "suiteb")) + { + SSL_CTX_set_security_level(ctx->ctx, 3); + SSL_CTX_set_cipher_list(ctx->ctx, "SUITEB128"); + } + else + { + msg(M_FATAL, "ERROR: Invalid cert profile: %s", profile); + } +#else + if (profile) + { + msg(M_WARN, "WARNING: OpenSSL 1.0.1 does not support --tls-cert-profile" + ", ignoring user-set profile: '%s'", profile); + } +#endif +} + void tls_ctx_check_cert_time(const struct tls_root_ctx *ctx) { @@ -1722,7 +1756,8 @@ print_details(struct key_state_ssl *ks_ssl, const char *prefix) } void -show_available_tls_ciphers(const char *cipher_list) +show_available_tls_ciphers(const char *cipher_list, + const char *tls_cert_profile) { struct tls_root_ctx tls_ctx; SSL *ssl; @@ -1742,6 +1777,7 @@ show_available_tls_ciphers(const char *cipher_list) crypto_msg(M_FATAL, "Cannot create SSL object"); } + tls_ctx_set_cert_profile(&tls_ctx, tls_cert_profile); tls_ctx_restrict_ciphers(&tls_ctx, cipher_list); printf("Available TLS Ciphers,\n");

[Openvpn-devel,v6] Add --tls-cert-profile option for mbedtls builds

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